1. Field of the Invention
The present invention relates to a separable door hinge for a motor vehicle door and including two hinge halves, attachable, respectively, to a door and an associated door pillar, at least partially retractable hinge pin for connecting the two hinge halves for pivotal movement relative to each other and for separation from each other, with the hinge pin having a first portion provided with a circumferential knurling for engaging a wall of a gudgeon bore of a gudgeon of one of the two hinge halves for fixedly securing the hinge pin against rotation in a finally assembled condition of the door and a second portion extending into a gudgeon bore of one gudgeon of another of the two hinge halves with a running fit.
2. Description of the Prior Art
Separable door hinges of the above-described type are well known and are widely used. There exist many different embodiments of the above-described type of a door hinge. Generally, during a preliminary assembly of the door, a portion of the hinge pin stud is pressfitted in a gudgeon of one of the two hinge halves, with the hinge pin knurling engaging the wall of the gudgeon of the one of the two hinge halves in a finally assembled condition of the door. In one of the conventional embodiments of a door hinge, in which one of the hinge halves has two spaced gudgeons between which a fork-shaped gudgeon of another of two halves is received, the hinge pin is completely withdrawn and then, during the final assembly, is inserted again. This embodiment of a door hinge has a number of drawbacks resulting from the fact that the parts of motor vehicle door hinges are mass-produced. From the mass-production of the door hinge components necessarily follows that the hinge halves and hinge pins are separate parts, are produced with small tolerances, and are assembled together without considering tolerance pairing. The danger of the use of conventional mass-produced door hinges consists in that in a relatively large number of door hinges, maximum permissible tolerances of the hinge pin and a gudgeon bore both positive any negative would coincide, resulting in significantly different forces of insertion and withdrawal of the hinge pin. This causes significant problems in vehicle assembly lines. Another problem, which is associated with the use of door hinges with a completely retractable pin, consists in that it cannot be insured that during the final assembly of the door, the original hinge pin would be inserted in the hinge, so that the tolerance pair of the hinge pin and the gudgeon bore may change during the final assembly of the door.
More favorable results are achieved with the use of another embodiment of the door hinge in which the hinge pin is not completely withdrawn during the temporarily lifting off of the door. In this embodiment, the hinge pin is only partially extracted during lifting of the door with a result that after the two hinge halves are separated, the hinge pin remains engaged in a gudgeon bore of one of the hinge halves. This insures that a hinge pin associated with a particular door hinge is always connected with the door hinge. That permits to avoid additional tolerance problem during re-assembly of the door. However, all of the problem, which are associated with mass production of the door hinges, in particular unfavorable tolerance deviations between a hinge pin and a gudgeon bore still remain.
Accordingly, an object of the present invention is to improve the separable motor vehicle door hinges in such a way that the insertion and pulling forces for insertion and retraction of a hinge pin during preliminary assembly are independent of all possible tolerance pairings of a hinge pin and a gudgeon bore.
Another object of the present invention is to reduce the manufacturing and assembly costs of production of the motor vehicle door hinges.